摘要
The chemical composition of the eolian deposits mainly depends on the material composition of the source area and post-depositional in-situ pedogenesis.In this study,systematic major element composition analysis has been made Shengli red earth section in Chengdu Plain,and compared with the geochemical characteristics of typical loess and paleosoil samples from western Sichuan Province.The research results show that,similar major element composition between the Chengdu Red Earth and the loess-paleosoil samples from western Sichuan,and they are also comparable to the average composition of the Upper Continental Crust.These suggest that the Chengdu Red Earth,as same as loess from western Sichuan,were all derived from well-mixed sedimentary protoliths which had undergone numerous upper crustal recycling processes.In the formation process of the Chengdu Red Earth,Ca and Na element experienced a large number of leaching and the content is very low,K and Mg also appeared different degree of leaching,explaining Chengdu Red Earth experienced chemical weathering process of plagioclase and potassium feldspar.Further study shows that,Chengdu clay has reached the later stage of medium degree of chemical weathering,and the vermiculated red soil has entered the strong weathering stage.From the chemical weathering parameters of the entire sequence,weakening chemical weathering intensity from 1.13 MaBP shows that Sichuan Basin and the surrounding area has gradually become drier since the mid-pleistocene,and has consistency with global climate change.